The actual reason is that the use of biological photos is a design choice meant to visually bridge connect artificial intelligence and human intelligence. These random biological photos help to convey the idea that AI is inspired by or interacts with human cognition, emotions, or biology. It’s also a marketing tactic: people are more likely to engage with content that includes familiar, human-centered visuals. Though it doesn’t always reflect the technical content, it does help to make abstract or complex topics more relatable to a larger/extended audience.